Methods for accessing to base station that uses SACK mechanism and apparatuses using the same

ABSTRACT

A method for mobile station accessing to a base station in a wireless communication system that uses selective acknowledgement mechanism, comprising: transmitting, an access probe from the mobile station to the base station; receiving, a message from the base station, wherein the message indicates parts of the plurality of data frames are not decoded by the base station; passing, an instruction from a MAC layer to a PHY layer of the mobile station, wherein the instruction is used to send a selective acknowledgement header; sending, the parts of data frames that are not decoded by the base station from the MAC layer to the PHY layer according to the message; and retransmitting the parts of the plurality of data frames.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the following U.S. Provisionalapplications, which are herein incorporated by reference:

SER. NO. FILING DATE 61/702,084 2012 Sep. 17 61/702,313 2012 Sep. 1861/703,004 2012 Sep. 19 61/713,381 2012 Oct. 12

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates in general to the field of wirelesscommunication, and more particularly to a new processing mechanism forSACK in CDMA 2000 1× wireless communication systems.

Description of the Related Art

In traditional TCP/IP wireless communication systems, if a data packetof a sequence is missing in transmission, more than one data packet maybe sent again, which means the data packets that have been received maybe retransmitted. As a result, the transmission efficiency is decreasedsignificantly. To improve that situation, a Selective ACKnowledgment(SACK) mechanism is proposed. Under SACK mechanism, only those missingpackets may be retransmitted, and all the other packets that have beenreceived accurately and correctly may be skipped. Accordingly, the SACKmechanism is able to make sure the receiver has responded to thetransmitter which packet is missing, which packet may be retransmitted,and which packets have been received and so on.

It is hoped that the SACK mechanism being introduced into CDMA 2000 1×wireless communication systems. And this kind of attempt is happened in1× Rev.F wireless communication systems and the same. 1× Rev.F is acommunication version of CDMA2000 1× wireless communication spec thatfocuses on optimizing and improving machine to machine (M2M)communications. However, a communication may not work normally even itintroduces the SACK mechanism according to spec.

Accordingly, it is desired to provide a new processing mechanism forSACK that may make the retransmission accurately with no confusion inCDMA 2000 1× systems.

SUMMARY OF THE INVENTION

A method of a mobile station to access to a base station in a wirelesscommunication system that uses selective acknowledgement mechanism,comprising: transmitting, an access probe from the mobile station to thebase station, the access probe including a plurality of data frames;receiving, a message from the base station, wherein the messageindicates parts of the plurality of data frames in the access probe arenot decoded by the base station; passing, an instruction from a MAClayer of the mobile station to a PHY layer of the mobile station,wherein the instruction is used to send a selective acknowledgementheader; sending, the parts of the plurality of data frames that are notdecoded by the mobile station from the MAC layer to the PHY layeraccording to the message; and retransmitting, by the mobile station tothe base station, the parts of the plurality of data frames.

A mobile station for accessing to a base station in a wirelesscommunication system that uses selective acknowledgement mechanism, themobile station comprising: PHY layer, configured to transmit an accessprobe from the mobile station to the base station, and receive a messagefrom the base station, wherein, the access probe including a pluralityof data frames, and the message indicates parts of the plurality of dataframes in the access probe are not decoded by the base station; and MAClayer, coupled to the PHY layer, and the MAC layer is configured to passan instruction to a PHY layer, and send the parts of the plurality ofdata frames that are not decoded by the base station to the PHY layeraccording to the message, wherein the instruction is used to send aselective acknowledgement header, wherein the access probes include afirst access probe.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features, and advantages of the presentinvention will become better understood with regard to the followingdescription, and accompanying drawings where:

FIG. 1 is a figurative diagram illustrating an access process of themobile station in conventional wireless communication system that useSACK mechanism;

FIG. 2 is a figurative diagram illustrating the format of the enhancedaccess probe in conventional wireless communication system;

FIG. 3 is a schematic diagram of a protocol stack according to anembodiment of the invention;

FIG. 4A is a figurative diagram illustrating an information transmittingprocess between the MAC layer and the PHY layer in mobile station inconventional wireless communication system that use SACK mechanism;

FIG. 4B is a figurative diagram illustrating an information transmittingprocess between the MAC layer and the PHY layer in mobile stationaccording to an embodiment of the invention;

FIG. 4C is a figurative diagram illustrating an information transmittingprocess between the MAC layer and the PHY layer in mobile stationaccording to another embodiment of the invention;

FIG. 5A combining 5B is a flow chart that shows the process of an accessattempt in a wireless communication system that uses SACK mechanismaccording to an embodiment of the invention;

FIG. 6 is a figurative diagram illustrating the process of an accessattempt in a wireless communication system that uses SACK mechanismaccording to one embodiment of the invention;

FIG. 7 is a figurative diagram illustrating the process of an accessattempt in a wireless communication system that uses SACK mechanismaccording to another embodiment of the invention.

DETAILED DESCRIPTION

The following description is presented to enable one of ordinary skillin the art to make and use the present invention as provided within thecontext of a particular application and its requirements. Variousmodifications to the preferred embodiment will, however, be apparent toone skilled in the art, and the general principles defined herein may beapplied to other embodiments. Therefore, the present invention is notintended to be limited to the particular embodiments shown and describedherein, but is to be accorded the widest scope consistent with theprinciples and novel features herein disclosed.

FIG. 1 is a figurative diagram illustrating an access process of themobile station in conventional wireless communication system that usesSACK mechanism. The mobile station 10 initiates an access attemptprocess to access the base station 20. When a mobile station wants toaccess a base station, the mobile station may initiate an accessattempt. During an access attempt, the mobile station may send a firstaccess probe to the base station. If the first access probe is notsuccessfully decoded by the base station, the mobile station may send asecond, a third, . . . a N^(th) access probe until one access probe issuccessfully decoded. A Enhanced Access Channel (EACH) or a ReverseEnhanced Access Channel (REACH) is used by the mobile station to sendthose enhanced access probes. In step 110, mobile station 10 sends afirst enhanced access probe on the REACH to base station 20, and theprobe has a plurality of data frames. In the embodiment, assuming thereare six REACH frames (frames 0, 1, 2, 3, 4, 5) in an enhanced accessprobe. However, there may be any number of data frames in an enhancedaccess probe according to the need of an application. SACK mechanism isintroduced in CDMA 2000 systems, especially in M2M wirelesscommunication systems that follow 1× Rev.F. According to theconventional SACK spec, there is a preamble and a SACK header in frontof the data frame as shown in FIG. 2.

In FIG. 2, the SACK header contains a 2-bit field, which is set as “01”to indicate this is a header instead of a data frame and to indicatethat the SACK is used. Therefore, in the 1^(st) transmission of theenhanced access probe (1^(st) probe), there is a preamble, a SACK headerand all the six frames (frames 0, 1, 2, 3, 4, 5). In step 120, assumingonly frames 0, 2 and 5 are successfully decoded at the base station 20.According to the conventional SACK mechanism, the base station 20 maysend back a SACK order to indicate which data frames are notsuccessfully decoded after receiving the probe. So, in step 130, thebase station 20 sends the 1^(st) SACK order to the mobile station 10 toindicate that data frames 1, 3, 4 are failed during transmissions.Therefore, in step 140, the mobile station 10 should prepare a secondaccess probe with a preamble, a SACK header and data frames 1,3,4. Next,in step 150, the mobile station 10 may send this second access probe tobase station 20. But, there may raise some problems when the mobilestation 10 prepares the second access probe in step 140 based onconventional SACK mechanism. Those problems will be discussedsubsequently in more detail.

FIG. 3 is a schematic diagram of a protocol stack according to anembodiment of the invention. The protocol stack 300 is incorporated withthe PHY (physical) layer 310, the MAC (media access control) layer 320,the LAC (link access control) layer 330 and the layer three 340.

Now the problem of how to pass the SACK header is discussed by referringFIGS. 4A to 4C. FIG. 4A is a figurative diagram illustrating aninformation transmitting process between the MAC layer and the PHY layerin mobile station in conventional wireless communication system thatuses SACK mechanism. FIG. 4A is a more detailed figurative diagramillustrating step 140 in FIG. 1. As shown in FIG. 4A, currently, SACK ishandled at PHY layer 340 of the mobile station 10. In step 130 of FIG.1, a SACK order is received by the mobile station 10. In step 410 ofFIG. 4A, the PHY layer 340 passes this SACK order. After that, in step420 a, the MAC layer 320 of the mobile station 10 may pass down aninstruction which is called a primitive to PHY layer 340. A primitive isan instruction that contains several instruction parameters to activatea series of specific operations so as to exchange information betweendifferent layers. Conventionally, the REACH data frame transmission iscontrolled by MAC layer via invoking primitive PHY-EACH.Request. Thisprimitive PHY-EACH.Request may pass down data frames to PHY layer fromMAC layer. Those parameters in PHY-EACH.Request include pwr_lvl,fpch_id, each_id, base_id, slot_offset, sdu, frame_duration, num_bitswith more explanations in the following:

pwr_lvl stands for the power level of the transmitter and may be set toPWR_LVL_(s);

fpch_id stands for the ID of paging channel and may be set toFCCCH_ID_(s);

each_id stands for the ID of EACH and may be set to EACH_ID_(s);

base_id stands for the ID of base station and may be set to BASE_ID_(s);

slot_offset stands for the transmitting time offset and may be set toACC_PREAMBLE_TX_SLOT_(s) mod 512;

sdu stands for the data frames that is transmitted;

frame_duration stands for the duration of the frame and may be set tothe duration of the frame; and.

num_bits stands for the number of bits for the data frames.

As the parameter“sdu” in primitive PHY-EACH.Request stands for the dataframes that is transmitted, the MAC layer 330 may pass only data frameswith no SACK header to PHY layer 340. For example, at step 140, themobile station 10 needs to prepare the 2^(nd) probe which contains theSACK header after the REACH preamble. But the MAC layer 330 may passdown the data frames after the REACH preamble according to theconventional primitive PHY-EACH.Request. This step is more detailed inFIG. 4A. In step 420 a, frames are passed down to PHY layer 340 via theparameter sdu in primitive PHY-EACH.Request, but the PHY layer expects aSACK header, therefore, in step 430 a, the PHY layer is confused. So,there needs a way to pass down the SACK header from the MAC layer to thePHY layer.

FIG. 4B is a figurative diagram illustrating an information transmittingprocess between the MAC layer and the PHY layer in mobile stationaccording to an embodiment of the invention. As shown in FIG. 4B. Thefirst solution is to configure MAC layer 330 to send to associated PHYlayer 340 a PHY-EACH.Request primitive with some parameters beingchanged to express the SACK header. In this embodiment, the originalprimitive PHY-EACH.Request is still used. The changed parameter is sdu,which may be changed to stand for the SACK header. Then, after sendingthe preamble, the SACK header may be passed from MAC layer to PHY layerdirectly via the primitive PHY-EACH.Request.

The second solution is to introduce a new primitive, as shown in FIG.4C. FIG. 4C is a figurative diagram illustrating an informationtransmitting process between the MAC layer and the PHY layer in mobilestation according to another embodiment of the invention. After receivedthe SACK order in step 410, this new primitivePHY-EACHSACKHeader.Request is sent from MAC layer 330 to PHY layer 340in step 420 c. The new primitive PHY-EACHSACKHeader.Request is used toindicate a SACK header may be sent after the preamble when needed. Whenthis new primitive is used, the MAC layer is aware that SACK header iscoming after the preamble. There might be many parameters in the newprimitive. In one embodiment, those parameters arePHY-EACHSACKHeader.Request (pwr_lvl, fpch_id, each_id, base_id,slot_offset, frame_duration).

pwr_lvl stands for the power level of the transmitter and may be set toPWR_LVL_(s);

fpch_id stands for the ID of paging channel and may be set toFCCCH_ID_(s);

each_id stands for the ID of EACH and may be set to EACH_ID_(s);

base_id stands for the ID of base station and may be set to BASE_ID_(s);

slot_offset stands for the transmitting time offset and may be set toACC_PREAMBLE_TX_SLOT_(s) mod 512; and

frame_duration stands for the duration of the frame and may be set tothe duration of the frame.

For the example in FIG. 4C, after the SACK order has been received instep 410, the MAC layer 330 may send a PHY-EACHSACKHeader.Request(pwr_lvl, fpch_id, each_id, base_id, slot_offset, frame_duration) to thePHY layer 340 to indicate that MAC layer 330 may send a SACK headernext. In step 430 c, the SACK header is passed to PHY layer 340.

Also, with the conventional spec, the PHY layer 340 in the mobilestation 10 is in charge of storing all the REACH frames contained in theprevious enhanced access probe, i.e., preambles, SACK headers, and allthe data frames 0,1,2,3,4,5. In the above two solutions, the SACK headermay be moved from PHY layer to MAC layer, since the PHY entity has alimit memory space. And, the MAC layer may set the SACK header properlyand pass down to PHY layer.

By using the above two solutions, the first problem about SACK header instep 140 of FIG. 1 is solved completely, and MAC layer is able tosuccessfully send the SACK header to PHY layer. The disclosedembodiments in the application may also be used in any the CDMA 2000 1×systems that use SACK mechanism.

However, the second problem is about the fault frames. The MAC layer 330is not aware how to pass the fault frames down to the PHY layer 340merely in the conventional spec. For example, at step 150 in FIG. 1,according to the SACK, the mobile station 10 needs to send frames 1, 3and 4 to the base station 20 without frames 0, 2 and 5. But, the MAClayer 330 may still pass all the six frames 0,1,2,3,4,5 down to PHYlayer 340 according to the conventional spec, which significantly causesconfusion to PHY layer 340.

To solve this second problem, the MAC layer may maintain an vectorduring one access attempt with length equals to the number of the REACHframes contained in the first enhanced access probe. For example, thevector may be named SACK[i] during one access attempt. The length ofSACK[i] is the number of the REACH frames contained in the very firstenhanced access probe. At the beginning, i.e., before sending the firstprobe, the entire vector may be set to 0, i.e. SACK[i]=0 (i=0, 1 . . .N−1). After sending a probe, the mobile station may check whether a newSACK Order is received. If a new SACK Order is received, the MAC layerin the mobile station may set the value of SACK[i] based on the SACKOrder. If SACK[i]==1 (i=0, 1 . . . N−1), it means the ith framecontained in the very first probe has been successfully decoded and maynot be passed down to PHY layer again. Otherwise, the MAC layer mayresend the ith frame to PHY. A SELECTIVE_ACK_BIT_MASK contained in theSACK Order indicates whether the corresponding frame is decodedcorrectly in the spec. After a new SACK Order is received, the MAC layermay set SACK[i] according to the SELECTIVE_ACK_BIT_MASK, as following:

j=0; for(i=0; i<N; i++) { if(SACK[i]==0) { SACK[i]= the value of the jthMSB of SELECTIVE_ACK_BIT_MASKs; j++; } }

FIG. 5A combining 5B is a flow chart that shows the process of an accessattempt in a wireless communication system that uses SACK mechanismaccording to one embodiment of the invention. In step 510, the mobilestation begins to access to a base station. In step 520, MAC layer ofthe mobile station determines whether it is the very first enhancedaccess probe in the access attempt. If it is, then in step 521, the MAClayer initializes SACK [i]=0, i=0, 1, . . . N−1, wherein N is the numberof frames contained in the very first probe of the access attempt, andthe process goes to step 530. If the determination of step 520 is no,then the process goes to step 530 directly. In step 530, the mobilestation determines whether a new SACK order has been received. If thedetermination is “yes” in step 530, then in step 531, MAC layer setsSACK [i] based on the SACK order, and the process goes to step 532. Ifthe determination of step 530 is no, then the process goes to step 532directly. In step 532, the mobile station sends the REACH preamble tothe base station. In step 540, the mobile station determines whetherSACK order has been received. If it has, then in step 541, the MAC layersends the SACK header to the PHY layer. If the determination of step 540is no, then the process goes to step 550 directly. In step 550, MAClayer determines whose entry value in SACK[i] is equal to zero, i.e.,whether SACK[i]=0, i=0, 1, . . . , N−1. In step 551, MAC layer passesthe ith frame, wherein SACK[i]=0, down to PHY layer, and the mobilestation sends it over REACH. If in step 550, there is on entry value inSACK[i] equal to zero i.e., SACK[i]≠0, i=0, 1, . . . , N−1, then in step560, the mobile station determines that if all the frames have beensent. If not all the frames have been sent, then the process goes tostep 550 to make the determinations again, until all the frames havebeen sent. The process terminates at step 570.

FIG. 6 is a figurative diagram illustrating the process of an accessattempt in a wireless communication system that uses SACK mechanismaccording to one embodiment of the invention. From the sake ofexplanations, there are still six REACH frames (frames 0, 1, 2, 3, 4, 5)in the first probe of the access attempt as the example of FIG. 1.Please note there may be any number of data frames in an enhanced accessprobe according to the need of application. In step 610, before sendingthe first probe, the MAC layer initiates SACK[i] to set each entry valueas zero, i.e., setting SACK[i]=0, i=0, 1, . . . 5, just as in step 521of FIG. 5A combining 5B. In step 620, the mobile station initiates the1^(st) enhanced access probe. In step 621, the base station receivesframes 0, 2 and 5 successfully. So, the base station may send a firstSACK order with the SELECTIVE_ACK_BIT_MASK set to 101001 back to themobile station. In step 622, the mobile station receives the first SACKorder, and the MAC layer sets the corresponding entry values as onebased on the first SACK order, i.e. setting SACK[i] to 101001 as in step531 of FIG. 5A combining 5B. Then in step 630, the mobile stationprepares to send the 2^(nd) enhanced access probe, so the MAC layerpasses down a SACK header (SH) to PHY layer to indicate that the comingframes are used for SACK transmitting. The MAC layer then passes downthe original frame 1,3,4 to PHY layer based on the vector SACK[i], andthe PHY layer sends them on REACH. In step 631, the frames in the 2^(nd)enhanced access probe may be renumbered=. In step 632, the base stationreceives frame 1 which is the original frame 3 successfully. Therefore,the base station may send a second SACK order with theSELECTIVE_ACK_BIT_MASK setting as 010 back to the mobile station. Instep 633, after receiving the second SACK order, the MAC layer isinformed of the original frame 3 have already been successfully decodedby the base station, and may set the SACK[i] to 101101 based on thesecond SACK order. Then in step 640, the mobile station prepares to sendthe 3^(rd) enhanced access probe, as shown in step 640, wherein the MAClayer passes down a SACK header (SH) and the original frame 1, 4 basedon the SACK[i] to PHY layer, and the PHY layer sends them on REACH. Instep 641, the frames in the 3^(nd) enhanced access probe may berenumbered. After that, the base station receives all the framessuccessfully and sends an ACK message back to the mobile station. Instep 642, the mobile station receives the ACK message and the accessprocess is successful.

The problem of how to pass the fault frames merely in step 150 of FIG. 1is solved, and MAC layer is able to send the fault frames to PHY layermerely. This new processing mechanism may be used in any CDMA2000 1×wireless communication systems that employ the SACK mechanism to preventthose systems from confusions.

Another unexpected problem, the third problem, may be raised if somedata frames at the end of the first probe are lost due to badcommunication environment. The base station may be unaware of totalnumbers of data frames of the probe delivered from the mobile station,such that the base station is unable to respond the mobile stationaccurate situations of those lost frames. For example, the first probeconsists of 6 REACH data frames as show in the example of FIG. 6. Afterthe first probe, in step 621, the base station successfully decodesframes 0 and 2, frames 1 and 3 are failed, and frames 4˜5 are lost. Thusthe base station may think the total number of data frames is 4. Then,the base station sets the SACK order based on the probe length to 4frames: 1010. In step 622, after receiving the first SACK Order, themobile station may re-transmit frames 1 and 3. The mobile stationdoesn't know how to deal with frames 4˜5. If frames 4 and 5 are notre-sent, then these two frames will be lost forever. If frames 4 and 5are re-sent and are still lost, then the base station will think themessage is correct if frames 1 and 3 are successfully decoded. So, it isvery important for the base station to know the exact number of REACHdata frames in the first access probe.

To solve the above problem, a new header may be introduced to indicatethe total number of REACH data frames contained in the first accessprobe of an access attempt. This new header may be named as SACK HeaderType II, and the conventional SACK header used in the conventional specand the above embodiments is called as SACK Header Type I. The SACKHeader Type II may be sent after the REACH preamble before the mobilestation receives the first SACK Order. The base station may send the1^(st) SACK Order only if this SACK Header Type II has been successfullydecoded, i.e., the base station gets the information of the number offrames in the first probe. After receiving the first SACK Order at themobile station, the mobile station may send SACK Header Type I insteadof the SACK Header Type II in the next probes to achieve the SACKtransmitting.

The MAC layer may use the following message format to assemble the SACKHeader Type I.

TABLE 1 Format of the Selective Retransmission Header Type I FieldLength (bits) SRT_HEADER_ID 2 SACK_CODE 8 RESERVED As required Wherein:SRT_HEADER_ID - An identifier indicates this frame is a SelectiveRetransmission Header Type I. The mobile station may set this field to‘10’. SACK_CODE - A code from the base station uniquely identify theaccess attempt for EACH selective retransmission operation. The mobilestation may set this field to SACK_CODES. RESERVED - Reserved bits. Themobile station may set this field so that the total number of bits inthis header fits the information bit number. The mobile station may setall the reserved bits to ‘0’.

In one embodiment of the application, the MAC layer may use thefollowing message format to assemble the SACK Header Type II.

TABLE 2 Format of the Selective Retransmission Header Type II FieldLength (bits) HEADER_IND 2 FRAME_NUM 6 Wherein: HEADER_IND An identifierindicates this frame is a Selective Retransmission Header Type II. Themobile station may set this field to ‘11’ FRAME_NUM To indicate thetotal number of REACH data frames contained in the message. The mobilestation may set this field to total number of REACH data frames.

The HEADER_IND field may always be set to ‘11’ to differentiate withSACK Header type I ‘10’ and data frame ‘00’ and ‘01’. The new headerSACK Header type II may be defined in PHY or MAC layer. But it is betterto put it in MAC layer spec. If the new header SACK Header type II isdefined in MAC layer, the conventional primitive PHY-EACH.Request may bereused with the sdu parameter set to the new header SACK Header type II.Or, new primitive may be introduced to pass down the new header tophysical layer.

If the mobile station decides to use SACK mechanism, it may include thenew header SACK Header type II right after the REACH preamble in theenhanced access probes before receiving the first SACK Order. And,before receiving the SACK Order, all the frames may be transmitted inthe probe. The base station may not send SACK Order back to the mobilestation until the new header is decoded. And, after decoding the newheader, the base station may set the SACK order accordingly. Afterreceiving the SACK Order, the mobile station may send the conventionalheader, SACK header type I, after the REACH preamble instead of the newheader SACK header type II. The following processing is the same asabove embodiments illustrated with reference of FIGS. 4-6. The aboveprocess may be illuminated more detailed with reference to FIG. 7.

FIG. 7 is a figurative diagram illustrating the process of an accessattempt in a wireless communication system that uses SACK mechanismaccording to another embodiment of the invention. For the sake ofexplanations, there are still six REACH frames (frames 0, 1, 2, 3, 4, 5)in the first probe in the access attempt as the examples of FIG. 1 andFIG. 6. Please note there may be any number of data frames in anenhanced access probe. In step 710, before sending the first probe, theMAC layer sets SACK[i], i.e., sets SACK [i]=0, i=0, 1, . . . 5, and themobile station initiates the 1^(st) enhanced access probe, wherein the1^(st) enhanced access probe has a REACH preamble (P), a SACK headertype II (SHII) and the data frames. In step 711, the base station onlyreceives frame 1 successfully, which means the base station does notreceive the SHII, and the base station does not know how many dataframes in the 1^(st) access probe. So, the base station may not send aSACK order back to the mobile station. In step 720, the mobile stationinitiates the 2^(nd) enhanced access probe, which still has a REACHpreamble (P), a SACK header type II (SHII) and the data frames. In step721, the base station receives the SHII and frame 3 successfully, so thebase station knows that there are six data frames in the probe and someof them are missing. Then, the base station may have two options insetting the SELECTIVE_ACK_BIT_MASK in the first SACK order. Option 1 isto set the SELECTIVE_ACK_BIT_MASK to 010100, which indicates the framesthat have been successfully decoded in the 1^(st) and 2^(nd) probes.Option 2 is to set the SELECTIVE_ACK_BIT_MASK to 000100, which indicatesthe frame that have been successfully decoded just in the 1^(st) probe.In step 730, the mobile station received the first SACK order and resetthe SACK[i] accordingly, and then initiates the 3^(rd) enhanced accessprobe. Since the base station have already know the number of the framesin the first probe, so 3^(rd) probe comprise SACK header type I (SHI).Then, the process goes as described in FIG. 6.

There is an alternative solution to inform the base station of the framenumber in the first probe, that is, the mobile station keeps checkingthe length of SELECTIVE_ACK_BIT_MASK in the SACK order with the numberof data frames in the previous probe. After receiving SACK Order, themobile station checks the length of SELECTIVE_ACK_BIT_MASK with thenumber of data frames in the previous probe. If it mismatches, themobile station knows that some frames are lost, and the mobile stationmay ignore the SACK Order and resends the previous probe. The basestation may re-determine the number of data frames in the probe. If itmatches, it means the base station knows the number of frames. Themobile station may resend the failed frames indicated by the SACK order.

Now, the base station is able to know the total number of data frames ofthe first probe. This new processing mechanism may be used in anyCDMA2000 1× wireless communication systems that use the SACK mechanismto prevent those systems from confusion.

Those skilled in the art may appreciate that they can readily use thedisclosed conception and specific embodiments as a basis for designingor modifying other structures for carrying out the same purposes of thepresent invention, and that various changes, substitutions andalterations can be made herein without departing from the scope of theinvention as defined by the appended claims.

What is claimed is:
 1. A method of a mobile station to access to a basestation in a wireless communication system that uses selectiveacknowledgement (SACK) mechanism, comprising: transmitting, a firstaccess probe from a PHY layer of the mobile station to the base station,wherein the first access probe includes a SACK header, a preamble, anddata frames; receiving, a SACK order sent from the base station, whereinthe SACK order indicates that parts of the plurality of data frames inthe first access probe are not decoded by the base station; afterreceiving the SACK order, sending from a MAC layer of the mobile device,an instruction to the PHY layer indicating that a subsequent SACK headermay be sent after a subsequent preamble as needed; sending thesubsequent SACK header from the MAC layer of the mobile station to thePHY layer of the mobile station; sending the parts of data frames thatare not decoded by the base station from the MAC layer to the PHY layeraccording to the message; and retransmitting, by the mobile station tothe base station, the parts of the plurality of data frames that are notdecoded by the base station.
 2. The method of claim 1, wherein SACKheaders are stored in the MAC layer.
 3. The method of claim 1, whereinof a first type of SACK header and a second type of SACK header, thesubsequent SACK header is the second type of SACK header.
 4. The methodof claim 3, wherein after the receiving the SACK order sent from thebase station, the method further comprises: transmitting the subsequentSACK header from the mobile station to the base station.
 5. The methodof claim 3, wherein the second type of selective acknowledgement headeris transmitted with an access probe other than the first access probe.6. The method of claim 5, wherein before receiving the SACK order sentfrom the base station, the method further comprises: the base stationsends the SACK order to the mobile station when the first type SACKheader is decoded.
 7. The method of claim 1, wherein the SACK header isa first type of SACK header comprised in the first access probe, and thefirst type of selective acknowledgement header comprises a first fieldindicating that the type of the SACK header is the first type, and asecond field indicating a total number of data frames in the firstaccess probe.
 8. The method of claim 1, wherein the wirelesscommunication system is a CDMA 2000 1× wireless communication system. 9.A mobile station for accessing to a base station in a wirelesscommunication system that uses selective acknowledgement (SACK)mechanism, the mobile station comprising: a PHY layer, configured totransmit a first access probe from the mobile station to the basestation, and receive a SACK order from the base station, wherein, thefirst access probe includes a SACK header, a preamble, and data frames,and the SACK order indicates that parts of the data frames in the accessprobe are not decoded by the base station; and a MAC layer, coupled tothe PHY layer, and configured to send an instruction to the PHY layerindicating that a subsequent SACK header may be sent after a subsequentpreamble as needed, sending the parts of data frames that are notdecoded by the base station from the MAC layer to the PHY layeraccording to the SACK order.
 10. The mobile station of claim 9, whereinthe PHY layer is further configured to retransmit the parts of the dataframes that are not decoded by the base station to the base station; andSACK headers are stored in the MAC layer.
 11. The mobile station ofclaim 9, wherein of a first type of SACK header and a second type ofSACK header, the subsequent SACK header is the second type of SACKheader.
 12. The mobile station of claim 11, wherein after the mobilestation receives the SACK order sent from the base station, the mobilestation transmits the subsequent SACK header to the base station. 13.The mobile station of claim 11, wherein the second type of SACK headeris transmitted with an access probe other than the first access probe.14. The mobile station of claim 11, wherein the wireless communicationsystem is a CDMA 2000 1× wireless communication system.
 15. The mobilestation of claim 9, the SACK header is a first type of selectiveacknowledgement header comprised in the first access probe, and thefirst type of SACK header comprises a first field indicating that thetype of the SACK header is the first type, and a second field indicatinga total number of data frames in the first access probe.
 16. The mobilestation of claim 15, wherein before the mobile station receives the SACKorder from the base station, the base station sends the SACK order tothe mobile station when the first type of SACK header is decoded.